import java.lang.annotation.Retention;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String s = scanner.nextLine();
        
        Solution solution = new Solution();
        System.out.println(s.indexOf(s));
    }
}

class Solution {
    public int maxOperations(String s) {
        int count = 0;
        int res = 0;
        char[] arr = s.toCharArray();
        for (int i = 0; i < arr.length; i++) {
            if(arr[i] == '1'){
                count++;
            } else if (i > 0 && arr[i - 1] == '1') {
                res += count;
            }
        }
        return res;
    }
}